Cycle controlling device



Api'il 2, 1946.

w. R. KovAcs 2,397,871

CYCLE CONTROLLING DEVICE Filed Feb. 8, 1943 INVENTOR WILL/AM {a KOVACJATTORNEY Patented Apr. 2, 1946 CYCLE CONTROLLING DEVICE William R.Kovacs, Cleveland, Ohio, asslgnor to The Cleveland Pneumatic ToolCompany, Cleveland, Ohio, a corporation of Ohio Application February 8,1943, Serial No. 475,093

Claims.

The present invention relates broadly to fluid actuated tools, but moreparticularly to fluid actuated riveting hammers of the type used for HD-setting rivets. Still more particularly, this invention deals with animproved cycle control or timing device for fluid actuated rivetinghammers.

The primary object of the invention is to provide an improved mechanismfor automatically controlling the cycle of operation of a rivetinghammer to an extent whereby fluid under pressure will be graduallysupplied until a predetermined maximum has beenreached to accelerate thehammer for upsetting the rivet, and the maximum pressure maintained fora predetermined interval of time before termination of the cycle.

Another object of the invention resides in the provision of an improvedcycle control or timing device having the above characteristics which isdesigned to accurately producerivet bucktails of uniform height anddiameter. In accordance with the present invention, the riveting cycleis pre-set and ceases automatically when the rivet has been upset,thereby avoiding the possibility of damage to the sheet and reducing toa minimum the number of rejects or damaged rivets.

A further object of the invention is to provide a mechanism of this typewhich can be attached to, or incorporated in, the handle of a fluidactuated riveting hammer with but slight modification of the tool.

Other objects and advantages more or less ancillary to the foregoingreside in the specific construction and aggroupment of the elementspeculiar to this structure, as will become apparent from a more completeexamination of this specification.

In the drawing which illustrates the invention:

Fig. 1 is a side elevational view of a riveting hammer with the improvedcycle control mechanism attached to the handle thereof, the handle andattachment being in section to show details of construction.

Fig. 2 is a view of a portion of the handle shown in Fig. 1 with theparts in another position.

Fig. 3 is a view similar to Fig. 2 with the parts in still anotherposition.

Fig. 4 is a perspective view of the slidable cylinder through which thepressure fluid flows, the same being removed from its housing.

Referring to the drawing for a more detailed description thereof, afluid actuated riveting hammer is generally designated by the referencenumeral I8 and includes a cylinder II having a piston (not shown)reciprocable therein and accylindrical shaped bore I6 which bore extendsI tive on a rivet set I 2 which is operatively mounted within the frontend of the cylinder II and secured in position by a suitable retainerI3. To the cylinder It is threaded, Or'OtherWise affixed, a handle I4provided in its upper end with a passage I5 which leads into thecylinder II for admitting motive fluid, such as compressed air, thereinto effect reciprocation of the piston and thereby cause rapidlyrecurring impacts to be delivered to the rivet set I2. The outer end ofthe passage I5 communicates with a relatively large outwardly throughthe end of the handle as clearly shown in Fig. 1 of the drawing.

A depressable trigger I! is slidably mounted in the handle I4 and ispreferably positioned adjacent the connecting end of said handle forconvenience of the operator handling the tool. A lever I8 has one end ispivotally attached to the inner end of the trigger II bya pin and slotconnection and said lever is pivotally connected at 20 to the handle I4.A cam-like portion M is formed integral with the lever l8 and isnormally in engagement with the upper end of a slidable supported rod 22for a purpose to be hereinafter more fully described.

The outlet end of the bore I6 is interiorly threaded as indicated at 23for receiving the threaded end 24 of a housing 25, said housingenclosing the cycle controlling mechanism about to be described. Asshown in Fig. 1 of the drawing, the housing 25 depends from the handleI4 and the rod 22 extends downwardly through the bore I6 and into saidhousing. The upper end of the rod 22 passes through a bushing 26provided in the handle I4 while the lower end of said rod carries avalve 21 which is normally urged into con tact with its seat 28 by meansof a compression spring 29. The housing 25 is adapted to be connectedwith a motive fluid supply conduit (not shown) through the threaded end30, and for convenience of operation, the threaded end 30 is pref erablydisposed so as to be in alignment with the bore 56 and threaded end 23.The threaded end 313 communicates with a recess 3I in which is housedthe compression spring 29.

The housing 25 is also formed with a cylindrical bore 32 whichcommunicates with the bore I6 and threaded end 24 through the passage33, and mounted for slidable movement within the bore 32, is a hollowcylinder or plunger 34 formed with a bottom wall 35 and sleeve 36 ofintegral construction. The cylinder 34 is formed with an opening 31 and,as more particularly shown in Fig. 4 of the drawing, said opening is ofsubstan- 2 asaaevi tially the same size throughout the major portion ofits length, but one wall thereof inclines inwardly toward the upper endof said cylinder to form a restricted opening 38 for a purpose to behereinafter described.

Also mounted within the bore 32, there is a stem 39 which carries avalve 48 on its upper end for controlling the passage of fluid from thebore 32 into the passage 33. Supported on the lower end of the stem 39which projects through an orifice 51 in the end wall of the housing 25is a lever 4!, the same being attached thereto by means of the nut 42. Awasher 43 is provided for spacing the rotated by the lever 4| and, aswill hereinafter appear, the cylinder 34 -is rotated when the positionof the opening 31 is to be changed. As will also hereinafter appear,entrance of air under pressure through the opening 31 of the cylinder 34will move said cylinder downwardly on the stem 39, the cylinder beingguided through engagement of the pin 44 within the slot 45. The

be upset and the operator depresses the trigger I1 for urging the rod 22outwardly through the action oi the lever it to unseat the valve 31,said valve being displaced from its seat against the pressure of thespring 3|. Air under pressure then enters the passage 54 and flows intothe cylinder 34 through the opening 31. By referring to Fig. 3 of thedrawing it will be noted that the valve 21 is in open position while thevalve 40 is in closed position and therefore the pressure of the airentering the cylinder 34 will urge said cylinder downwardly on the stem39 until the lower end of the sleeve 38 contacts the stem '39, adjacentits lower end, supports a piston 46 and said piston is formed with adepending portion 41 of a reduced diameter through which passes a pin 48for locking the piston to the stem 39. Thus, the piston 46 is supportedon the lower end of the stem 39 for movement therewith in a longitudinalas well as a rotary direction. The end wall '49 01' the housing 25 isformed with a cup-shaped valve seat 50 through which the stem 39projects, and is adapted to support therein the tapered end 5| of thepiston 46 during one phase of the cycle. By this construction, thereduced end of the piston 46 acts as a valve for preventing the escapeof motive fluid through the orific 51, said orifice acting as a vent forthe lower end of the bore 32, communication therewith being providedthrough the recess 53. A second vent 52 is formed substantiallyintermediate the ends of the bore 32 whereby said bore may beadditionally vented at the termination of the cycle. Interposed betweenthe upper face of the piston 46 andthe bottom wall of the cylinder 34,there is a spring 58 which normally maintains said cylinder in the upperend of the bore 32. A similar spring 59 is interposed between the bottomface of the piston 46 and the bottom wall 49 for maintaining said pistonin its normal posi tion shown in Figs. 1 and 3.

A horizontally extendingpassage 54 is formed above the valv 21 andcommunicates with the vertical bore 32. With the valve 21 in openposition, air under pressure is admitted through the inlet 30 and flowsthrough the passage 54 and opening 31 of the cylinder 34. A restrictedpassage communicates with the passage 54 adjacent its discharge end andthe lower end of the passage 55 communicates with the bore 32 adjacentits lower end. The upper end of the passage 55 is controlled by means ofa needle valve or the. like 66, while the discharge end thereof iscontrolled by the piston 46.

In the operation of the device, with the parts in the position shown inFig. 1 of the drawing, the rivet set is positioned adjacent th rivet tomination' of the cycle.

upper face of the piston 46. The cylinder 34 continues to movedownwardly on the stem 38 and forces the piston 46 downwardly until thetapered end 5| thereof is seated on its seat 60. As clearly shown inFig. 2 of the drawing, downward'movement of the cylinder 34 willcollapse the spring 58 and likewise downward movement of the piston 46will collapse the spring 68. During the downward movement of thecylinder 34, the stem 39 remains stationary until contact is madewiththe piston 46 and as said piston is forced downwardly, the stem 39will be similarly moved to unseat the valve 40, thereby allowing the airto be discharged through the passage 33 into the bore I6 and passage 5for action on the hammer. At this phase of the cycle, the parts are allin the position and in the relation shown in Fig. 2 and it will beobserved that the restricted opening 38 of the cylinder 34 is thendisposed substantially opposite to the passage 54. Since the lower endof the restricted passage 66 has been uncovered by movement of thepiston 46, a certain amount of air under pressure will be discharged inthe area between the bottomwall 35 of the cylinder 34 and the upper faceof the piston 46 and the pressure therein is gradually built up untilthe cylinder 34' is caused to move upwardly on the stem 39. The pressureof air on the face of the piston 46 will maintain said piston in itsFig. 2 position until the cylinder 34 has returned to its normalposition at which time the air within the bore 32 will be vented throughthe outlet 52 whereupon the pressure of the spring 59 will be sumcientto return the piston 46 to its normal position to close the dischargeend of the passage 55. Of course, upward movement of the piston 46 willcause the stem 39 to be moved upwardly to seat the valve 40 and therebyshut oil? the flow of air to the hammer.

A feature of th present invention provides for the gradual flow of airunder pressure to the hammer until a maximum pressure has beenreachedand the maximum pressure maintained for a predetermined interval of timebefore ter- The restrictedu opening 38 of the cylinder 34, with saidcylinder in the Fig. 2 position, will cause a gradual feeding of airunder pressure to the hammer until said cylinder begins to rise on thestem 39 in the manner previously described. As the cylinder rises theopening 38 will move upwardly beyond the passage 54 and graduallyincrease in size until the full opening 31 is opposite the passage 54 atwhich time maximum pressure is being fed to the hammer and that pressurewill be maintained until the piston 46 moves from the Fig. 2 to the Fig.3 position for closing the valve 40.

The'lever 4| forms the means for controlling the size of th opening 31that is exposed to the passage 54 and the size of the opening governsthe amount of pressure being supplied to the hammer. As is understood,the larger the size of the opening the larger the volume of pressure tobe supplied and conversely the smaller the size of the opening thesmaller the volume of pressure that will be supplied to the hammer. Ifdesired, a suitable gauge can be attached to the outer wall of thehousing 25 and the upturned end 60 of the lever 4| will point to thegauge and serve as an indicator for denoting the size of the opening asth stem 39 and cylinder 34 are rotated under the action of the lever 4!.

The upper end of the restricted passage 55 is controlled by a needlevalve or the like 56 and is adjusted by the operator. Restricting theinlet opening to the passage 55 will delay the action of the cylinder 34providing a longer time cycle and conversely an unrestricted openingwill increase the flow of air through said passage to speed up the timecycle.

From the above description when taken in connection with theaccompanying drawing, it will be readily apparent that there has beenprovided an improved mechanism for automatically controlling the cycleof operation of a riveting hammer to an extent whereby pressure will begradually applied until a predetermined maximum has been reached toaccelerate the hammer and the maximum pressure maintained for apredetermined interval of time before termination of the cycle. Thewidth of the opening 31, 38 governs the amount of pressure to be fed tothe hammer the reduced end 38 providing for gradually building up thepressure to the hammer. The entire operation is automatic and is beyondthe control of the operator after the trigger has been depressed. Inview of the fact that the riveting cycle is pre-set through the mediumof the handle 4| and needle valve 56, and will cease automatically whenthe rivet has been upset, there is very little possibilit of damage tothe sheet as well as a reduction to a minimum of the number of rejectsor damaged rivets. Moreover it will be seen that a riveting tool orhammer embodying the control means herein disclosed can be used forrapidl driving a series of individual rivets in succession, and thatsince the riveting operation is automatically controlled and terminatedall of the rivets of the series will be subjected to substantiall thesame riveting operation and will be upset to substantially an identicalextent.

Although the foregoing description is necessarily or a detailedcharacter, in order to com;- pletely set forth the invention, it is tobe understood that the specific terminology is not intended to berestrictive or confining and it is to be further understood that'variousrearrangements of parts and modifications of structural detail may beresorted to without departing from the scopepr spirit of the inventionas herein claimed.

I claim:

1. In mechanism of the character described, a housing having a bore witha valve seat at one end thereof, a stem in said bore carrying a'valvecooperating with said seat, a spring active upon said stem for biasingit toward valve closing position, a piston fixed upon said stem movablein said bore, a plunger in said bore between said valve and said pistonslidable on said stem, said housing having an intake for pressure fluidcommunicating with said bore functioning to exert pressure on saidpiston for opening the valve, and functioning thereafter to exertpressure between said piston and said plunger for gradually moving theplunger away from the piston, and y means controlled by the lattermovement of the plunger for relieving the pressure on said piston andthereby permitting said spring to shift the valve to closed position.

2. In mechanism of the character described, a housing having a bore witha valve seat at one end thereof, a stem in said bore carrying a valvecooperating with said seat, a spring active upon said stem for biasingit toward valve closing position, a piston fixed'upon said stem movablein said bore, a plunger in said bore between said valve and said pistonslidable on said stem, said housing having an intake for pressure fluidcommunicating with said bore functioning to exert pressure against thevalve side of said plunger, and against the valve side of said pistonfor opening the valve, and functioning thereafter to exert pressurebetween said piston and said plunger for gradually moving the plungeraway from the piston, and means controlled by the latter movement of theplunger for relieving the pressure on said piston and thereby permittingsaid spring to shift the valve to closed position.

3. In mechanism of the character described, a

'housing having a bore with a valve seat at one end thereof, a stem insaid bore carrying a valve cooperating with said seat, a spring activeupon said stem for biasing it toward valve closing position, a pistonfixed upon said stem movable in said bore, a plunger in said borebetween said valve and said piston slidable on said stem, said housinghaving an intake for pressure fluid with a relatively large portcommunicating with said bore on the valve side or said plunger and arelatively small port communicating with the bore on the opposite sideof the plunger, said plunger being effective in response to flow throughsaid larger port for shifting said stem to open the valve, flow throughsaid smaller port entering the space between said piston and saidplunger for holding the piston in valve open position and graduallmoving the plunger away from the piston, and means controlled by saidplunger in its latter movement for relieving the pressure on said pistonand permitting said spring to shift the valve to closed position.

4. The mechanism defined in claim 3 characterized in that said piston,in its position corresponding with closed valve position, covers andblocks said smaller port and uncovers it in valve open position.

5. The mechanism defined in claim 1 characterized in that spring meansare provided for assisting the movement of said plunger away from saidpiston.. I

. WIIJ'JAM R. KOVACS.

